This article discusses the search for evidence of supersymmetry at CERN's Large Hadron Collider. While the discovery of the Higgs boson was a success, scientists have yet to find any signs of supersymmetric particles as predicted by the theory. The LHC will restart early next year with high stakes - either find evidence supporting supersymmetry or face a potential crisis in physics if the theory is not validated. The article explores how the failure to find supersymmetry so far has challenged physicists and the models they have developed to extend the Standard Model of particle physics.

1. © 2014 Scientific American

4. May 2014 Volume 310, Number 5
ON THE COVER
2 Scientific American, May 2014 Photograph by Greg Ruffing
The Higgs boson was just the beginning. Scientists at
CERN’s Large Hadron Collider also desperately want to
find evidence of supersymmetry, a theory of matter that
posits the existence of a brand-new world of fundamental
particles. To the surprise of many, no signs have yet been
found.When the LHC starts up early next year, the stakes
will be high: find supersymmetry, or face a crisis in physics.
FEATURES
PARTICLE PHYSICS
34 Supersymmetry and the Crisis in Physics
For decades physicists have been working on
a beautiful theory that would lead them to a deeper
under­standing of the quantum world. But soon
they will face a moment of truth, when their theory
is either proved or found to be lacking.
By Joseph Lykken and Maria Spiropulu
MEDICINE
40 Cancer’s Off Switch
By releasing the brakes that tumor cells place on
the immune system, researchers are developing
a new generation of more powerful treatments
against malignancy. By Jedd D. Wolchok
PALEONTOLOGY
46 Fossil GPS
Luck has played a big part in many of the world’s
great fossil discoveries. New models predict where
the bones are and put serendipity in the backseat.
By Robert L. Anemone and Charles W. Emerson
NEUROSCIENCE
52 Is Anybody in There?
Scientists are getting through to patients who appear
to lack consciousness. By Adrian M. Owen
ENGINEERING
58 Shape-Shifting Things to Come
Flexible, one-piece machines could soon make
today’s assemblages of rigid parts look like antiques.
By Sridhar Kota
OCEANOGRAPHY
66 The Great Coral Grief
The person who discovered more than 20 percent
of the world’s coral species now fears the reefs are
in deeper trouble than most people realize.
By Iain McCalman
MATHEMATICS
70 The Oracle
Insights from the unpublished papers of mathematics
prodigy Srinivasa Ramanujan spurred an unlikely
protégé to solve long-standing puzzles. By Ariel Bleicher
58
© 2014 Scientific American

6. 4 Scientific American, May 2014
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DEPARTMENTS
6 From the Editor
8 Letters
12 Science Agenda
The myth of the compassionate execution. By the Editors
13 Forum
Biology is making it harder for scientists to reproduce
one another’s experiments. By Veronique Kiermer
14 Advances
The cosmic blowup. Volcanoes restrain climate change.
Physics of curly locks. How a fallow buck gets the girl.
31 The Science of Health
Even without tobacco, poorly regulated e-cigarettes
may pose unique dangers. By Dina Fine Maron
33 TechnoFiles
A little outrage over new technology can be a good thing.
By David Pogue
76 Recommended
Marvelous man-made materials that make our world.
Animals as architects. A history of li­­quor. True stories
of brain trauma and recovery. By Clara Moskowitz
78 Skeptic
An infant’s sense of right and wrong. By Michael Shermer
80 Anti Gravity
A statistician writes a book about probabilities—
what are the odds? By Steve Mirsky
82 50, 100 150 Years Ago
84 Graphic Science
Tick- and mosquito-borne diseases go farther afield.
By Mark Fischetti
O N T H E W E B
The Future of the Internet
This year marks the 25th anniversary of the invention of
the World Wide Web. Where will the Internet go from here,
especially considering the challenges to net neutrality?
Go to www.ScientificAmerican.com/may2014/internet
21
31
76
INGOARNDT Abrams (termitetowers)
© 2014 Scientific American

8. 6 Scientific American, May 2014
From the Editor
Mariette DiChristina is editor
in chief of ScientificAmerican.
Follow her onTwitter @mdichristina
Illustration by Nick Higgins
BOARD OFADVISERS
Leslie C.Aiello
President, Wenner-Gren Foundation
for Anthropological Research
Roger Bingham
Co-Founder and Director,
The Science Network
G.Steven Burrill
CEO, Burrill Company
Arthur Caplan
Director, Division of Medical Ethics,
Department of Population Health,
NYU Langone Medical Center
George M.Church
Director, Center for Computational
Genetics, Harvard Medical School
Rita Colwell
Distinguished University Professor,
University of Maryland College Park
and Johns Hopkins Bloomberg School
of Public Health
Drew Endy
Professor of Bioengineering,
Stanford University
Ed Felten
Director, Center for Information
Technology Policy, Princeton University
KaighamJ.Gabriel
Corporate Vice President,
Motorola Mobility, and Deputy, ATAP
Harold“Skip”Garner
Director, Medical Informatics and
Systems Division, and Professor, Virginia
Bioinformatics Institute, Virginia Tech
Michael S.Gazzaniga
Director,SageCenterfortheStudyofMind,
University of California, Santa Barbara
DavidJ.Gross
Professor of Physics and Permanent
Member, Kavli Institute for Theoretical
Physics,University of California, Santa
Barbara (Nobel Prize in Physics, 2004)
LeneVestergaard Hau
Mallinckrodt Professor of
Physics and of Applied Physics,
Harvard University
Danny Hillis
Co-chairman, Applied Minds, LLC
Daniel M.Kammen
Class of 1935 Distinguished Professor
of Energy, Energy and Resources Group,
and Director, Renewable and Appropriate
Energy Laboratory, University
of California, Berkeley
Vinod Khosla
Partner, Khosla Ventures
Christof Koch
CSO, Allen Institute for Brain Science
Lawrence M.Krauss
Director, Origins Initiative,
Arizona State University
Morten L.Kringelbach
Director, Hedonia: TrygFonden
Research Group, University of Oxford
and University of Aarhus
Steven Kyle
Professor of Applied Economics and
Management, Cornell University
Robert S.Langer
David H. Koch Institute Professor,
Department of Chemical
Engineering, M.I.T.
Lawrence Lessig
Professor, Harvard Law School
John P.Moore
Professor of Microbiology and
Immunology, Weill Medical
College of Cornell University
M.Granger Morgan
Professor and Head of
Engineering and Public Policy,
Carnegie Mellon University
Miguel Nicolelis
Co-director, Center for
Neuroengineering, Duke University
MartinA.Nowak
Director, Program for Evolutionary
Dynamics, and Professor of Biology and
of Mathematics, Harvard University
Robert E.Palazzo
Dean, University of Alabama at
Birmingham College of Arts and Sciences
Carolyn Porco
Leader, Cassini Imaging Science
Team, and Director, CICLOPS,
Space Science Institute
Vilayanur S.Ramachandran
Director, Center for Brain and Cognition,
University of California, San Diego
Lisa Randall
Professor of Physics, Harvard University
Martin Rees
Astronomer Royal and Professor
of Cosmology and Astrophysics,
Institute of Astronomy, University
of Cambridge
John Reganold
Regents Professor of Soil Science
and Agroecology, Washington
State University
Jeffrey D.Sachs
Director, The Earth Institute,
Columbia University
Eugenie C.Scott
Chair, Advisory Council,
National Center for Science Education
Terry Sejnowski
Professor and Laboratory Head
ofComputationalNeurobiologyLaboratory,
Salk Institute for Biological Studies
Michael Shermer
Publisher, Skeptic magazine
Michael Snyder
Professor of Genetics, Stanford
University School of Medicine
Michael E.Webber
Co-director, Clean Energy Incubator,
and Associate Professor,
Department of Mechanical Engineering,
University of Texas at Austin
StevenWeinberg
Director, Theory Research Group,
Department of Physics,
University of Texas at Austin
(Nobel Prize in Physics, 1979)
George M.Whitesides
Professor of Chemistry and
Chemical Biology, Harvard University
NathanWolfe
Director,GlobalViralForecastingInitiative
R.JamesWoolsey
Chairman, Foundation for the Defense
of Democracies, and VenturePartner,
Lux Capital Management
AntonZeilinger
Professor of Quantum Optics,
Quantum Nanophysics, Quantum
Information, University of Vienna
JonathanZittrain
Professor of Law and of Computer
Science, Harvard University
Does Physics Have a Problem?
It was 2012, and physicists had just announced the big news:
CERN’s Large Hadron Collider had delivered what looked
like (and was later confirmed to be) a Higgs particle, the
capstone of a decades-long search to complete the so-
called Standard Model of particle physics—a discovery
that would lead the following year to a Nobel Prize. Naturally,
many scientists immediately eyed the next piece of the puzzle that
they anticipate the LHC will uncover. “I’m still hanging tough,
hoping for supersymmetry,” said John Ellis of King’s College Lon-
don at the time, referring to the theory of matter that many physi-
cists thought would supplant the Standard Model.
Since then, however, the search for “superpartner” particles
that would help describe why particles have the masses they do
and would solve the mystery of dark matter has led to disap-
pointments. So far, as Joseph Lykken and Maria Spiropulu relate
in their cover story, “Supersymmetry and the Crisis in Physics,”
the “results from the first run of the LHC have ruled out almost
all the best-studied versions” of the theory. A higher-power run is
due in 2015, but there is no guarantee it will yield the answers.
Then what? Turn to page 34.
While we wait for the foundational picture of how the uni-
verse works to take better shape, we can watch ma­­chines develop
the ability to take different forms here on Earth. In “Shape-­Shif­t­
ing Things to Come,” starting on page 58, Sridhar Kota chronicles
efforts to employ elastic, or compliant, design in our man-made
contraptions. Instead of using many rigid parts in complex and
often inefficient systems, as is done today, such designs can dis-
tribute loads across flexible devices made of fewer parts. The
materials could enable such applications as bendable aircraft
wings and snake robots, and their use would improve efficiency
and durability in our engineered creations. They may not solve
some of our profound questions about the universe, but they
could make things easier here in the meantime.
C I T I Z E N S C I E N C E
Last Chance to Enter
Entries close on May 12 for the Google Science Fair, which
includes a chance to win the $50,000 Scientific American
Science in Action Award. The international competition is
open to students ages 13 to 18. Science in Action honors
a project that can make a practical difference by tackling an
environmental, health or resources challenge; the prize in­­
cludes a year of mentoring to continue to advance the win­
ning work.Details can be found at ScientificAmerican.com/­
education/science-in-action ­­—M.D.
© 2014 Scientific American

10. Letters
editors@sciam.com
8 Scientific American, May 2014
DISTRUSTED DEVICES
David Pogue asks how we can know if
privacy switches on the iPhone actually
do anything in “In Tech We Don’t Trust”
[TechnoFiles]. We could know this if the
software were not closed source but open
to inspection. By far the biggest advantage
of open source software is that people all
over the world can review it to see that it
does what it says it does—and only that.
River Att
Manchester, England
SIMULATED CELLS
In “Simulating a Living Cell,” Markus W.
Covert describes the remarkable achieve­
ment of the first complete computer mod­­­­­­
el of an entire single-celled organism, the
bacterium Mycoplasma genitalium. Would
it be feasible now to sequentially disable
as many as possible of the bacterium’s 525
genes while still allowing the model cell to
divide, as a means of investigating how an
even simpler organism might have exist­
ed in the past and point the way to a pos­
sible route back to the origin of life?
Gordon Lee
via e-mail
COVERT REPLIES: I and others are in
fact considering how to go about deleting
genes to find viable strains that have few-
er genes than M. genitalium. It’s an inter-
esting problem for a few reasons: First,
there are many potential solutions. Sec-
ond, the order matters—every gene that
you knock out has consequences; in some
cases, one gene has to be taken out before
another one can be, or else the cell dies. We
are hoping that we can use our models to
generate insight into the best approach
and possibly come up with a design for a
cell based on that insight.
One of our toughest problems is sim-
ply that each simulation (a cell dividing
one time) takes about 10 hours, so gener-
ating the number of simulations that we
would need is computationally daunting.
With luck, we will have an answer in a
few years.
RENEWABLE LETHARGY
Vaclav Smil’s otherwise excellent article
on the factors that make a transition to
re­­­newable energy slow and gradual, and
on the policies that might hasten it [“The
Long Slow Rise of Solar and Wind”], does
not mention the huge global subsidies
enjoyed by fossil fuels (some half a tril­
lion dollars annually). This makes it diffi­
cult for renewable energy to compete.
Understanding of the urgency of switch­
ing to renewable energy sources and im­
proving efficiency is greatly impeded by
this distortion of the economy.
Peter Elliston
Clontarf, Australia
Among the evidence that we will be
slow to move to renewables, Smil cites
the 50 to 60 years it took to transition
from wood to coal and from coal to oil. I
am reminded of a caveat that comes with
strategic-planning statements from in­
vestment advisers when quoting fund
performance: past performance is no
guarantee of future performance.
Those periods of transition took place
in circumstances significantly different
from the transition to natural gas, begin­
ning in 1930. And the circumstances since
then are drastically different. One differ­
ence is the explosive growth in popula­
tion in the 20th century. Another is the
growth in demand/expectation of domes­
tic consumerism. But the main difference
is the knowledge of the consequences of
human activity vis-à-vis carbon fuels. This
knowledge would indicate that if human­
ity indulged in the luxury of letting the
unregulated capitalist market proceed at
its own rate, we might well be doomed to
an unlivable planet before we complete
the coming transition.
There are enormous obstacles to un­
dertaking a transition plan. Those who
hold legal title to carbon-based, climate-
changing fuels are unwilling to relin­
quish the profits from their reserves even
if the well-being of the biosphere re­
quires that they do so. And humans have
a tendency to think that what they ob­
serve in their lifetime is normal and can
be reasonably expected to continue even
when it is clearly a historical anomaly.
Richard Fahlman
Texada Island, B.C.
HELIOCENTRIC HOSTILITY
The scientific evidence cited in argu­
ments against Copernican heliocentric
cosmology in the 16th and 17th centuries,
as described in “The Case against Coper­
nicus,” by Dennis Danielson and Christo­
pher M. Graney, ought not lead us to ig­
nore the enormous—and tragic—social
con­­sequences of religious opposition to
this revolutionary idea. Christianity long
ago allied itself with a geocentric cosmol­
ogy, with Man at the apex of a special Cre­
ation, po­ssessed of an immortal soul and
capable by perfect free will of choosing
good or evil.
The Copernican, Darwinian and Freud­
ian revolutions have laid waste this com­
forting ideology. The rejection of evolu­
tion, of climate change, of even the possi­
bility of benefits from genetically modified
organisms reflects a self-destructive dis­
trust of science that stems largely from
January 2014
“The biggest
advantage of
open source software
is that people
all over the world
can review it
to see that it does
what it says it does—
and only that.”
river att manchester, england
© 2014 Scientific American

12. 10 Scientific American, May 2014
Letters
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Robin Lloyd
bruised religious sensibilities. This wound
to modern society will not yield to scientif­
ic education alone.
Jeff Freeman
Rahway, N.J.
THE HIDDEN MIND
While it was insightful, “Our Uncon­
scious Mind,” John A. Bargh’s article on
how unconscious processes affect our de­
cision making, left me a little unsatisfied.
He ends one paragraph by stating that
“to make our way in the world, we need
to learn to come to terms with our uncon­
scious self,” but he neglects to offer sug­
gestions. I believe meditation has helped
me a lot.
Joe Christie
via e-mail
Bargh describes a study asking parti­
cipants to judge fitness for public office
based on fleeting glimpses of photographs
of the candidates. I was disappointed that
many interesting follow-up questions were
not pursued. For instance: Is there a pre­
dictable IQ level above which a person
would merely laugh when asked to parti­
cipate in such an idiotic task? Is the level of
the participants characteristic of the vot­­
ing population as a whole?
Steve Munden
via e-mail
DIMINISHED DISEASE
In the 50, 100 150 Years Ago column,
compiled by Daniel C. Schlenoff, the item
called “Battling Trachoma,” excerpted from
a January 1964 article, refers to nearly 500
million people then being infected with
that disease.
Your readers might like to know that
since that time, the number of people in­
fected has dropped to 21.4 million. Where­
as some of the reduction is from general
im­­provement in hygiene and living condi­
tions, much of it is the result of a global
initiative to eliminate blinding trachoma
sponsored by the World Health Organiza­
tion, which builds on the SAFE strategy:
surgery for trichiasis (inward-turning eye­­
lashes), antibiotics, facial cleanliness and
environmental improvement.
Hugh Taylor
Melbourne School of Population
and Global Health, Australia
© 2014 Scientific American

14. Science Agenda by the Editors
Opinion and analysis from Scientific American’s Board of Editors
12 Scientific American, May 2014 Illustration by Logan Faerber
The Myth of the
Compassionate
Execution
The use of drugs to carry out
capital punishment is putting
bona fide medical patients at risk
In January the state of Ohio executed the convicted rapist and
murderer Dennis McGuire. As in the other 31 U.S. states with
the death penalty, Ohio used an intravenously injected drug
cocktail to end the inmate’s life. Yet Ohio had a problem. The
state had run out of its stockpile of sodium thiopental, a once
common general anesthetic and one of the key drugs in the exe-
cutioner’s lethal brew. Three years ago the only U.S. supplier of
sodium thiopental stopped manufacturing the drug. A few labs
in the European Union still make it, but the E.U. prohibits the
export of any drugs if they are to be used in an execution.
Ohio’s stockpile of pentobarbital, its backup drug, expired in
2009, and so the state turned to an experimental cocktail con-
taining the sedative midazolam and the painkiller hydromor-
phone. But the executioner was flying blind. Execution drugs
are not tested before use, and this experiment went badly. The
priest who gave McGuire his last rites reported that McGuire
struggled and gasped for air for 11 minutes, his strained breaths
fading into small puffs that made him appear “like a fish lying
along the shore puffing for that one gasp of air.” He was pro-
nounced dead 26 minutes after the injection.
There is a simple reason why the drug cocktail was not test-
ed before it was used: executions are not medical procedures.
Indeed, the idea of testing how to most effectively kill a healthy
person runs contrary to the spirit and practice of medicine. Doc-
tors and nurses are taught to first “do no harm”; physicians are
banned by professional ethics codes from participating in exe-
cutions. Scientific protocols for executions cannot be estab-
lished, because killing animal subjects for no reason other than
to see what kills them best would clearly be unethical. Although
lethal injections appear to be medical procedures, the similari-
ties are just so much theater.
Yet even if executions are not medical, they can affect medi-
cine. Supplies of propofol, a widely used anesthetic, came close
to being choked off as a result of Missouri’s plan to use the drug
for executions. The state corrections department placed an or­­der
for propofol from the U.S. distributor of a German drug manu-
facturer. The distributor sent 20 vials of the drug in violation of
its agreement with the manufacturer, a mistake that the distrib-
utor quickly caught. As the company tried in vain to get the state
to return the drug, the manufacturer suspended new orders. The
manufacturer feared that if the drug was used for lethal injec-
tion, E.U. regulators would ban all exports of propofol to the U.S.
“Please, Please, Please HELP,” wrote a vice president at the dis-
tributor to the director of the Missouri corrections department.
“This system failure—a mistake—1 carton of 20 vials—is going to
affect thousands of Americans.”
This was a vast underestimate. Propofol is the most popular
anesthetic in the U.S. It is used in some 50 million cases a year—
everything from colonoscopies to cesareans to open-heart surger-
ies—and nearly 90 percent of the propofol used in the U.S. comes
from the E.U. After 11 months, Missouri relented and agreed to
return the drug.
Such incidents illustrate how the death penalty can harm ordi-
nary citizens. Supporters of the death penalty counter that its
potential to discourage violent crime confers a net social good. Yet
no sound science supports that position. In 2012 the National
Academies’ research council concluded that research into any
deterrent effect that the death penalty might provide is inherently
flawed. Valid studies would need to compare homicide rates in the
same states at the same time, but both with and without capital
punishment—an impossible experiment. And it is clear that the
penal system does not always get it right when meting out justice.
Since 1973 the U.S. has released 144 prisoners from death row
because they were found to be innocent of their crimes.
Concerns about drug shortages for executions have led some
states to propose reinstituting the electric chair or the gas cham-
ber—methods previously dismissed by the courts as cruel and
unusual. In one sense, these desperate states are on to some-
thing. Strip off its clinical facade, and death by intravenous in­­
jection is no less barbarous.
SCIENTIFIC AMERICAN ONLINE
Comment on this article at ScientificAmerican.com/may2014
© 2014 Scientific American

15. May 2014, ScientificAmerican.com 13
Forum by Veronique Kiermer
Commentary on science in the news from the experts
Illustration by Sam Falconer
Veronique Kiermer is director
ofAuthor and Reviewer Services
at Nature Publishing Group.
Eureka Once, Eureka Twice
Biology is making it harder for scientists to reproduce one another’s experiments
Science works by iteration. Scientists repeat their peers’ work
and build on their findings. The literature of peer-reviewed sci-
entific papers is the record of this step-by-step process. In recent
years, however, prominent reports have suggested that many sci­­­
entists are not able to replicate others’ published results. Is sci­­
entific progress going wrong on an unprecedented scale? Before
we jump to that conclusion, it would help to consider the chang-
ing nature of science itself—particularly biology.
Basic biomedical research and its translation into therapeu-
tic interventions to cure diseases are at the center of this issue.
In an ideal world, academic scientists identify targets for
drugs—typically proteins involved in disease—and industry sci-
entists look for agents that interfere with those targets’ func-
tion. In reality, more often than not, industry scientists find that
they cannot replicate the effects seen by academics in a suffi-
ciently robust way to justify drug development. Worse, many
promising drug candidates fail in phase II clinical trials when
their efficacy is put to the test.
The world seemed simpler in the 1970s, when molecular biol-
ogy brought us concepts such as “gene A leads to protein B,
which leads to function C.” Thinking this way, scientists uncov-
ered amazing mechanistic insights and, sometimes, designed ef­­
fective drugs—the cancer drug Gleevec is the poster child of that
reductionist approach. Wouldn’t it be nice if drug discovery al­­
ways went this way?
Those first drugs, however, were low-hanging fruit. Biology is
much more complicated than simple schematics. Biological pro-
cesses do not work in linear ways independently of one another
but in tightly interconnected networks. In each branch of these
networks, layers of regulatory controls constantly change the na­­
ture and abundance of the molecular players. We know little
about the inner workings of human cells.
To illustrate how little, consider how genes are controlled. The
modern study of gene regulation started in the 1950s, but re­­
searchers only started to unravel the complex array of histone
modifications that fine-tune chromatin control of gene expression
20 years ago. The fact that RNA interference, another mode of
gene regulation, is pervasive has only been realized in the past 10
years. What else don’t we know yet?
Laboratory biologists deal with complexity on a daily basis.
Mice bred with identical DNA behave differently. Two cells grow-
ing side by side in a petri dish cannot be considered identical. In
the variable environment of the cell, it is difficult to distinguish a
change that is meaningful to a process from one that is unrelat-
ed. Working in a modern lab also entails using sensitive appara-
tuses, rare technical skills and biological reagents—antibodies
and enzymes, for example—which are themselves variable.
In such noisy systems, it is easy to mistake a chance observa-
tion for a robust, biologically meaningful effect. Biologists have
to undertake large studies that can guarantee the statistical sig-
nificance of observations, and they need self-critical analysis to
avoid inadvertent biases. Scientists cannot be too careful to
avoid falling prey to their own enthusiasm.
In that regard, they need the support of their institutions and
the journals that publish their results. Some journals, such as
Nature, have introduced checklists to ensure that scientists con-
sider and report key information about experiments. (Scientific
American is part of Nature Publishing Group.) Still, research in­­
stitutions should provide more training and supervision of
younger scientists. Institutions and funders should manage their
incentive systems to limit undue pressures on researchers and
promote best practices.
The need for replicating results is as important as ever. But
it is inevitable that results obtained in one cell line might not
exactly match those in another. They in turn might not be com-
pletely predictive of the observations in animal models, let alone
human beings. The literature of published results is still strong.
To keep it that way, the scientific community cannot afford to
be complacent. It must pay attention to the professionalism of
re­­searchers and take into account the complexity of biology.
SCIENTIFIC AMERICAN ONLINE
Comment on this article at ScientificAmerican.com/may2014
© 2014 Scientific American

16. 14 Scientific American, May 2014 ScientificAmerican.com/may2014/advancesFURTHER READINGS AND CITATIONS
ADVANCES
Dispatches from the frontiers of science, technology and medicine
SLIMFILMS
Score one for inflation. The idea that
the universe ballooned rapidly after the big
bang received a boost in March, when physicists confirmed
a prime prediction of inflation theory. The Background Imaging
of Cosmic Extragalactic Polarization 2 (BICEP2) experiment at
the South Pole found evidence for primordial gravitational waves,
ripples in the fabric of space and time, that were created when the
early universe swelled. The discovery is not just a major validation
of inflation, physicists say, but a good way to narrow down the
many possible versions of inflation that might have taken place.
“This really collapses the space of plausible inflationary models
by a huge amount,” says Marc Kamionkowski of Johns Hopkins
University, who was not involved in the discovery but who co-­
predicted back in 1997 how these gravitational-wave imprints
could be found.“Instead of looking for a needle in a haystack,
we’ll be looking for a needle in a bucket of sand.”
BICEP2 found a pattern called primordial B-mode polarization
in the light left over from just after the big bang known as the cos­
mic microwave background.This pattern, basically a curling in the
po­­larization, or orientation of the electric field, of the light, can be
created only by inflation-induced gravitational waves.“We’ve found
the smoking-gun evidence for inflation, and
we’ve also produced the first image of gravitational
waves across the sky,”says Chao-Lin Kuo of Stanford University,
who designed the BICEP2 detector and co-leads the collaboration.
Such a groundbreaking finding requires confirmation from
other experiments to be truly believed, physicists say. Neverthe­
less, the result was heralded as a huge win for cosmology.“There’s
a chance it could be wrong, but I think it’s highly probable that
the results stand up,” says Alan Guth of the Massachusetts In­­
stitute of Technology, who first predicted inflation in 1980.
Physicists are now parsing the finding for clues about the
timing and details of inflation. The BICEP2 measurement sug­
gests that inflation began a trillionth of a trillionth of a trillionth
of a second after the big bang, a time when the universe would
have been so energetic that all the fundamental forces of nature—
the electromagnetic, strong and weak forces, with the exception
of gravity—might have been unified into a single force. The new
results could also quell any remaining doubters of inflation.“If this
discovery is confirmed,” says Andrei Linde of Stanford, one of the
main au­­thors of inflation,“inflationary theory does not have any
real alternatives.” —Clara Moskowitz
COSMOLOGY
Our
Inflated
Universe
Traces of primordial
gravitational waves
could tell us how and
when the early universe
went through its
precipitous expansion
BLOWING
ITSELF UP:
A rapidly expanding
universe spawns
gravitational waves
that stretch
and compress
spacetime.
© 2014 Scientific American

18. 16 Scientific American, May 2014 ScientificAmerican.com/may2014COMMENT AT
The Little Volcanoes That Could
Many small eruptions over the past decade or so
have helped restrain climate change
On Valentine’s Day, Indonesia’s Mount
Kelud blew its top and coated villages up
to 500 kilometers away with ash. At the
same time, the eruption injected a small
but consequential amount of sulfur diox­
ide 28 kilometers up into the stratosphere.
Tiny droplets of sulfuric acid then reflect­
ed away incoming sunlight, helping to cool
the planet. Such “small” eruptions—along
with others at places like Manam, Soufri­
ère Hills, Jebel at Tair and Eyjaf­jallajökull,
to name a few of the 17 between 2000 and
2012—have helped slow the pace of global
warming, according to work published in
Nature Geoscience. (Scientific American is
part of Nature Publishing Group.)
“The uptick in early 21st-century vol­
canism clearly was a contributing factor
to the hiatus,” says atmospheric scientist
Benjamin Santer of Lawrence Livermore
National Laboratory, lead author of the
report. The volcanoes did not act alone.
There was also an unusually quiescent
sun, air pollution from China’s coal-fired
power plants and the mysterious work­
ings of the ocean. Santer adds, “The net
impact was to offset part of the human-
caused greenhouse gas warming.”
In the meantime, global warming con­
tinues to gather strength, hidden behind
volcanoes that may shutter their tops at
any moment. Based on supersized erup­
tions such as Mount Pinatubo in the Phil­
ippines in 1991, reflective aerosols would
then fall to Earth within a few years at
most, leaving the planet exposed to the
full heat-trapping effects of greenhouse
gases from human activities.
If the volcanoes do not do their part,
a last resort may be required—bring our
own aerosols. Advocates of one form of
geoengineering want to step in, injecting
sulfate aerosols in the stratosphere to
augment or replace eruptions. Such deli­­b­­
erate tinkering with planetary-scale sys­
tems has been proposed as a fallback plan
if climate change were to turn catastroph­
ic, though at the cost of the stratospheric
layer that helps to shield life from ultravi­
olet light. Sulfuric acid high in the sky has
the unfortunate side effect of eliminating
ozone. But given the inertia in reducing
greenhouse gas pollution, the debate
around geoengineering will undoubtedly
linger longer than the aftermath of these
small volcanic eruptions. —David Biello
GLOBAL WARMING
GETTYIMAGES
© 2014 Scientific American

19. May 2014, ScientificAmerican.com 17
ADVANCES
DAVIDPONTON Corbis
A Symbol of Royalty Makes
a Tentative Comeback
Back in 1997, the conservative National
Wilderness Institute petitioned the U.S.
Fish and Wildlife Service to remove the
Hawaiian hawk, or ‘io (Buteo solitarius),
from the Endangered Species Act (ESA).
The fws finally moved forward on the
proposal in February, asking for public
comments on the pending delisting.
The hawk joined the endangered spe-
cies list in 1967, fewer than six months
after passage of the original Endangered
Species Preservation Act, the predecessor
to the current ESA. The only modern
hawk native to Hawaii, the ‘io, in 1967,
was limited to just a small portion of
Hawaii Island (aka the Big Island). The
original causes of its decline are unknown,
but today it has expanded its range across
nearly 60 percent of the island.
More than 40 years of legal protection
and recovery efforts seem to have helped
the Hawaiian hawk. Since 1967 the spe-
cies’ population has grown to around
3,000—a number that seems to have
been stable since 1998 despite continued
urbanization on the Big Island and risks
from invasive species.
But the newspaper West Hawaii Today
found that many Hawaiians do not think
the ‘io should be delisted. The owner of
an animal sanctuary told the paper that
people still shoot the birds—she recently
rehabilitated two hawks that had been
shot with a BB gun—and that their habi-
tat continues to shrink. One Hawaiian
cultural practitioner said he sees the birds
less often than he did 10 or 20 years ago.
The hawks are valued in Hawaiian culture
as a symbol of royalty.
Even if the hawk is delisted, it will be
protected under the Migratory Bird Trea-
ty Act, a 1918 federal law. The fws would
also act as a monitor for at least five years
to make sure that new threats do not
emerge—oversight that is needed.
Hawaii is, after all, known as the “extinc-
tion capital of the world.” —John R. Platt
EXTINCTION
COUNTDOWN
HAWAIIAN
HAWK
© 2014 Scientific American

20. 18 Scientific American, May 2014
ADVANCES
FROM“HOMININFOOTPRINTSFROMEARLYPLEISTOCENEDEPOSITSATHAPPISBURGH,U.K.,”
BYNICKASHTONETAL.,IN PLOSONE, VOL.9,NO.2,ARTICLENO.E88329;FEBRUARY7,2014
COMPUTER GRAPHICS
The Physics of
Long, Loose Tresses
Simulating a single spiraling hair strand
may prove a boon to computer animators
In DreamWorks Animation’s Shrek franchise,Princess Fiona
almost exclusively wears her hair pulled back.The character’s
preference for braids has more to do with physics than fashion.
Letting a cartoon character’s hair down requires calculating a
string of complex equations to create a realistic effect,so com-
puter animators often just opt for short hair and updos rather
than long,loose tresses.Likewise,most animated characters
turn up on the big screen with straight locks because rendering
them in three dimensions is a simpler mathematical task.
Animators’tool kits may be about to expand,and a con-
vincing rendition of curls might one day abound in features by
DreamWorks and Pixar.Ateam of researchers recently untan-
gled the physics of a single strand of curly hair,publishing the
results in Physical Review Letters. “This is the first time someone
described the full 3-D configuration of a single naturally curved
hair,”says co-author Pedro Reis,an assis-
tant professor of mechanical engi-
neering and of civil and environ-
mental engineering at the
Massachusetts Institute of
Technology.“I would attri-
bute that to the fact that
the geometry of a curly hair
is highly nonlinear—
a word we often use for
something complicated.”
Reis and his colleagues did
not set out to model curly hair.
They wanted to study curvature of
long,thin structures.Think of submarine
cables,oil and gas pipes,and even the tiny tails on bacteria.
The team first laid hollow,tubular molds out straight or
wrapped them around cylindrical objects ranging in diameter
from 3.2 centimeters to one meter.Then they injected the
molds with a rubberlike material,which dried to produce flexi-
ble rods with different curvatures.They suspended the rods to
study how gravity affected their shape.With curls hanging one
beside another,they realized the rods bore a striking similarity
to the single strands that combine to form coifs ranging from
rail-straight to the kinks ofAfro-textured hair.
The researchers carried out some 11,000 computer simula-
tions,usingtheresultstocreateaphasediagramdepictingdiffer-
ent geometric shapes a hanging strand will assume as a function
offourproperties:curvature,weight,lengthandstiffness.Eventu-
allysuchatoolcouldbeincorporatedintoanimationsoftware,but
other groups will first have to investigate how a full head of curly
hair interacts with itself and with wind and other outside forces.
The model could also calculate curvature of steel pipes or
other spooled material.“We were engineers trying to solve
practical,useful problems from the start,”Reis says.“I’m not a
professional hairstylist—I’m bald,actually.”—Rachel Nuwer
ARCHAEOLOGY
Ancient Footprint
English mud captures an ancestral stroll
Archaeologists working on the eastern coast of England have
found a series of footprints that were made by human ancestors
sometime between one million and 780,000 years ago. Pressed
into estuary mudflats now hard with age, these prints are the
oldest ones known outside of Africa, where humanity arose.
Scientists discovered the prints in early May 2013, at a sea-
side site in Happisburgh. High seas had eroded the beach sand
to reveal the mudflats underneath. The team had to act quickly
to record the tracks before they, too, eroded. The researchers
used a technique called multi-image photogrammetry and laser
scanning to capture the prints in three dimensions.
In a paper published this past February in PLOS ONE, Nick
Ashton of the British Museum and his colleagues reported that
analysis of the footprints—which show impressions of the arch,
ball, heel and toes of several individuals—suggests they were left
by a party of five as they walked south along a large river. Based
on the apparent foot lengths, they ranged in height from 0.93 to
1.73 meters, evidence that the group was composed of both
adults and youngsters. The researchers estimated the body mass
of the adults at 48 to 53 kilograms.
Exactly which species of early human left the trails is un­­
known because no human remains have turned up at the site.
Yet judging from the antiquity of the prints, a likely candidate is
Homo antecessor, a species known from the site of Atapuerca in
Spain that had body dimensions similar to those reconstructed
for the largest Happisburgh footprint makers.
Happisburgh is the oldest known site of human occupation
in northern Europe. Previous excavations there have turned
up dozens of flint tools that these ancient people may have used
to butcher animals or process their skins. Where had the track
makers come from, and where were they going? Perhaps con-
tinuing erosion of the coastline will reveal more clues to the
lives they lived. —Kate Wong
Illustrations by Thomas Fuchs
© 2014 Scientific American

22. 20 Scientific American, May 2014
ADVANCES
SOURCE:NASA/SETI/JASONROWE
NumberofNewPlanets
0
50
100
150
200
300
400
500
600
700
Non-Kepler discoveries (green)
1996 1998 2000 2002 2004 2006 2008 2010 2012 Jan.–Feb. 2014
Kepler discoveries (blue)
Kepler discoveries
recorded on
Feb. 26, 2014 (light blue)
Discovery Year
ASTRONOMY
Kepler’s Afterlife
Data from the damaged spacecraft reveal new worlds
NASA’s Kepler space telescope was launched in 2009 and stopped
taking data last year after a mechanical failure. Yet in its relatively
short lifetime, it has offered up a wealth of discovery. In February
scientists announced a new harvest that brought Kepler’s tally of
discovered planets to nearly 1,700. “This is the biggest haul ever,”
says Jason Rowe of the nasa Ames Research Center, who co-led
the research. The scientists studied more than 1,200 planetary
systems and validated 715 planets. All the new worlds are members
of multiplanet systems—stars with more than one orbiting satellite.
Researchers used a new method for weeding out false signals.
Kepler searched for planets by measuring dips in a star’s brightness,
which occur when a planet passes in front of it. This technique, called
the transiting method, is very accurate, but sometimes a nonplanet
can fool the telescope. One of the most common reasons for a “false
positive” is an eclipsing binary—a pair of orbiting stars that sometimes
cross in front of each other from our perspective.
Stars with a single planet can be hard to distinguish from eclipsing
binaries. But multiplanet systems are far less likely to be frauds. “It
happens, but it’s unlikely that you have two eclipsing binaries in the
background of the same star,” says Francois Fressin of the Harvard-
Smithsonian Center for Astrophysics, who was not involved in the
study. It is also possible, albeit extremely unlikely, to have an eclipsing
binary and a star with a planet lying right on top of each other.
Rowe and his colleagues tried to weed out false signals by examin­
ing light from the candidate planets. They looked for a particular
signature known as a moving centroid: an off-center point of light
that could be created only by an eclipsing binary, not by a planet.
What remained among the trove of ample discoveries: a potentially
rocky world; an odd binary star system where
each star has plan­ets of its own; and cramped
systems where the multiple planets are each
gravi­tationally tug­ging one another around.
“Of course, we have every type of planetary
system in our vali­dated set that people can think
of except the perfect Earth analogue,” Rowe
says. For now that remains Kepler’s holy grail.
—Clara Moskowitz
BY T H E N U M B E R S
4.4
billionAge in years
of the oldest piece
of Earth’s crust
ever discovered:
an ancient zircon crystal
from Australia
that is only
160 million years
younger
than our
solar system.
SOURCE: “Hadean Age for
a Post-Magma-Ocean Zircon
Confirmed by Atom-Probe Tomography,”
by John W. Valley et al.,
in Nature Geoscience,
Vol. 7; March 2014
Graphic by Jen Christiansen
© 2014 Scientific American

23. May 2014, ScientificAmerican.com 21
COURTESYOFNASA,JPLANDUNIVERSITYOFARIZONA
W H AT I S I T ?
The resemblance is uncanny, but no,these aren’t Starfleet logos emblazoned on
planetVulcan.Perhaps fittingly,though,this nasa Mars Reconnaissance Orbiter image
shows a section of an active dune field on Mars.Strong winds blowing in a single direc-
tion resulted in massive piles of basaltic sand about 200 meters wide and 20 meters tall
that formed crescent-shaped“barchan dunes.”The imaging method—infrared shifted
color—portrays them with a blue tint,but to the naked eye they would actually appear
as neutral gray mounds sitting on the Red Planet’s signature colored backdrop.
This group of barchans rests at 23° N latitude and just west of MawrthVallis,one
of the oldest valleys on Mars,famous for its clay mineral deposits that form only in the
presenceofwater.Asoutlandishastheymayappear,thesedunesarenostrangertoEarth.
Bar­chanscommonlyformindesertshere,inplacessuchasNewMexico,NamibiaorTurk­­
istan,whereRussiannaturalistAlexandervonMiddendorfintroducedthemtothescientif-
icliteratureas“barchans,”awordborrowedfromaCentralAsianlanguage.—AnnieSneed
© 2014 Scientific American

24. 22 Scientific American, May 2014 ScientificAmerican.com/may2014COMMENT AT
ALEXWILD
ADVANCES
ENTOMOLOGY
A Pontoon
of Pupae
A species of ant escapes floods
on a raft made of its babies
“In the ant’s house, the dew is a flood,”
an old proverb tells us. Yet for floodplain-
dwelling ants, a little dew is nothing.
When a real flood arrives, some ant
species are known to evacuate their nest
and self-assemble into rafts that float to
dry ground. Swarm behavior is common
in ants: some species even build living
bridges to let their kindred march atop.
When it comes to raft building, the
behavior has been observed in fire ants,
but scientists at the University of Lau­
sanne in Switzerland have discovered
a peculiar design in living rafts of
an­­other species, which builds boat
bot­­­­toms with its young. Using babies
as flotation devices is not as much
a threat to propagating ant genes as
you would think.
This species of floodplain-dwelling
ant, Formica selysi, nests throughout the
Pyrenees and the Alps. The queen ant
lives for about 10 to 15 years and ex­­
periences a Noah’s ark–like flood an
average of two or three times in her
lifetime. During a flood, the worker ants
collect the brood—immobile eggs, larvae
and pupae—into a pile, and then another
three or four layers of workers climb
atop them and hold onto the babies with
their mandibles. The queen assumes her
place in the protected middle of the raft.
Placing the brood on the bottom,
where it is most at risk of drowning,
seems like a bad idea. After all, along with
the queen, offspring are the most valuable
members of the colony because their
survival will determine its evolutionary
success. “The conventional wisdom would
be that the workers would put the brood
in the middle of the raft with the queen,”
says postdoctoral student Jessica Purcell,
who led the research.
Purcell and her colleagues mimicked
flood conditions in their laboratory with
F. selysi ants they collected along the
Rhône River banks in Switzerland. All
ants rafted in artificial flood conditions,
regardless of whether or not they had
a brood; those with no babies at hand
built their boat base out of worker ants
instead. After the flood subsided, the raft
without a brood had more unresponsive
worker ants and they took more time to
recover, which may explain why this spe-
cies recruits its buoyant youth.
Surprisingly, the ant babies did not
appear to suffer at all from their watery
chores. Those that made up the raft bot-
tom survived just as successfully as the
brood control group kept on dry land. The
tremendous buoyancy of ant babies, most
likely the result of high fat content, pre-
vents them from sinking when they have
to carry their parents on their back. So in
the ant world, offspring are not so use-
less: it’s the mommies and daddies who
are the hangers-on. —Annie Sneed
SWARM: Some ant species build liv-
ing rafts or bridges, such as this over-
pass constructed by Eciton burchelli.
© 2014 Scientific American

25. May 2014, ScientificAmerican.com 23
NEUROSCIENCE
It Takes a Prion
to Remember
An infamous protein helps to
explain how memory works
The protein family notorious for causing
neurogenerative diseases such as Parkin-
son’s—not to mention mad cow—appears
to play an important role in healthy cells.
“Do you think God created prions just to
kill?”muses Eric R.Kandel of Columbia
University.“These things have evolved ini-
tially to have a physiological function.”
Kandel’sworkonmemoryhelpedto
revealthatanimalsmakeanduseprionsin
theirnervoussystemsaspartofanessential
function:stabilizingthesynapsesinvolved
withforminglong-termmemories.These
naturalprionsarenotinfectious,butona
molecularleveltheychainupexactlythe
samewayastheirdisease-causingbreth-
ren.(Someresearcherscallthem“prion-
like”toavoidconfusion.)Nowneuroscien-
tistKausikSioftheStowersInstitutefor
MedicalResearchinKansasCity,Mo.,oneof
Kandel’sformerstudents,hasshownthat
theprion’sactionistightlycontrolledbythe
cellandcanbeturnedonwhenanewlong-
termmemoryneedstobeformed.
Once the prion’s chain reaction gets
started,itisself-perpetuating,andthusthe
synapse—whereneuronsconnect—canbe
maintained after the initial trigger is gone,
perhapsforalifetime.Butthatstilldoesnot
explain how the first prion is triggered or
why it happens at only certain of the syn-
apses,whichplayacrucialroleinforming
memories.Si’swork,publishedFebruary11in
PLOSBiology, tracesthebiochemistryofthis
protein-preservation process in fruit flies,
showinghowthecellturnsonthemachinery
responsibleforthepersistenceofmemory—
and how the memory can be stabilized at
just the right time and in the right place.
Si and his colleagues focused on a pro-
tein called Orb2A—its human equivalent is
CPEB—that functionsas a prion in the flies.
Aseries of molecular interactions results in
a phosphate becoming attached to Orb2A
butonly when an electrical impulse is tar-
geted to a particular synapse among the
multitude that can populate a neuron.The
specificity allows the prion chain reaction
to turn on at the specific time and place
needed,stabilizing some synapses but not
others—and perhaps explaining why some
of our memories fade.—Beth Skwarecki
© 2014 Scientific American

28. 26 Scientific American, May 2014 ScientificAmerican.com/may2014COMMENT AT
ADVANCES
ANIMAL BIOLOGY
He Who
Hollers
Fastest
Gets
the Girl
A fallow buck judges a rival’s
call to tell whether he can be
trounced in a mating contest
When a male fallow deer wants to mate,
he isn’t shy about letting everyone around
him know. The males, also called fallow
bucks, can produce their mating calls as
many as 3,000 times each hour during
the mating season. Those calls serve two
functions: to attract females and to deter
rival males. Yet there is more hidden in
the groans of fallow bucks than first
meets the ear, according to a new study
in Behavioral Ecology.
Every October around 25 bucks gather
in Petworth Park in England’s county
of West Sussex, where each stakes out
a territory, hoping to entice a female at
a feral conclave of romance, combat and
deer calling, an event known as a lek.
“Leks are really rare in mammals, and
they’re really rare in ungulates. Fallow
deer are the only species of deer that we
know that lek,” says Alan McElligott of
Queen Mary, University of London, who
oversaw the study.
Mating calls reveal information
about the caller, such as body size or
dominance rank, which is useful both to
interested females and to rival males—
and every conceivable type of fallow
deer utterance turns up at the lek. In one
study, McElligott found that the quality
of groans decreased over time. “The
mature bucks stop eating for a couple
of weeks,” over the course of the lek,
McElligott explains, so “they are really
worn out.”
That fatigue is reflected in their calls,
but do other males notice? Because the
lek is such a spectacle, the deer in Pet­
worth Park are accustomed to human
interlopers, which allowed Queen Mary
postdoctoral scholar Benjamin J. Pitcher
to cart a sound system around without
interrupting the festivities.
Broadcasting prerecorded calls, he
discovered that deer can distinguish
those made early in mating season, when
males are still healthy, from those made
later, once they are fatigued. If a rival
male sounds exhausted, it might be
worth trying to displace him from his
territory. If a subordinate male is to chal­
lenge a dominant one, it is best to be sure
that he can actually win.
—Jason G. Goldman
BY T H E N U M B E R S
Percentage of U.S. adults
who used Facebook in 2013,
nearing the 10th anniversary of
the social media site going live.
SOURCE: “6 New Facts about Facebook,” by Aaron Smith.
Pew Research Center, February 3, 2014
57
© 2014 Scientific American

29. May 2014, ScientificAmerican.com 27
COURTESYOFRICCARDOSATTA
IMAGE PROCESSING
Cameraprints
A unique camera “signature”
to identify online criminals
New developments in tracing particular
photographs to the cameras that snapped
them might provide the basis for a forensic
methodofcatchingpedophileswhodistribute
child pornography anonymously on the
Internet.It could also help law-enforcement
agencies identify smartphone thieves who
take pictures with the stolen gadgets and
then post the images online.
It has been known since 2006 that tiny
variations in the silicon chip–based camera
sensors create differences in response to
light that leave a signature“noise”pattern
(below right) on every photo that can be
matched to a specific camera and cannot be
removed.“It is not currently possible to per-
fectlyseparatetheimagefromthenoise,mod-
ifythenoiseandthenadditbacktotheimage,”
says Riccardo Satta,a scientific officer at the
EuropeanCommissionJointResearchCenter’s
Institute for the Protection and Security of
the Citizen.At a recent privacy conference in
Brussels,Satta presented work showing that
sensor-pattern noise persists when photos
are modified and uploaded to social media.
Investigators have long known of other
identifiersthatdigitalcamerasinsertintoimag-
es as they convert a stream of light into digital
bits.But none are as reliable for tracing the
source of an image as sensor-pattern noise.
Inapreliminarystudyof2,896images
takenfrom15differentsocialnetworksorblog
accounts,Satta and his colleague Pasquale
Stirparo found that a photograph could be
linked half the time to a specific camera as a
mostprobablematch.Theyalsodiscoveredthat
asetofimagescouldbeaccuratelygroupedac­­
cordingtotheoriginatingcamera90percentof
the time,with a false positive rate of 2 percent.
These statistics are not good enough to
use at a trial.But the technique could help
select targets for investigation,especially
when presented along with other information
found on social networks,such as location
and friend lists. —Wendy M.Grossman
© 2014 Scientific American

30. 28 Scientific American, May 2014 ScientificAmerican.com/may2014COMMENT AT
COURTESYOFU.S.PATENTANDTRADEMARKOFFICE(camerapatent);COURTESYOFEMERGENCY(Strada)
QA
“Millions of
People Are
Suffering”
A prominent Italian heart
surgeon talks about his plan
to build free, state-of-the-art
hospitals in Africa
Building on the success of your
Salam Center for Cardiac Surgery
in Sudan, you plan to open 10 free
hospitals throughout Africa. Fund-
ing will come from Emergency,
the NGO you founded in 1994. Can
you talk about your approach?
If I look at the health indicators in
Africa, I see something that is very,
very similar to what the situation was
in Europe 200 years ago. In
other words, medicine
has not developed.
Millions of people
are suffering and
dying, and so we
have to ask, How
do we reverse
this trend?
How will you do
things differently?
Most health facilities
in Africa are complete­
ly filthy. There’s no hy­­
giene whatsoever. The
staff doesn’t go to work;
patients are at­­tended
by family. Nothing’s
free of charge; noth­
ing’s available.
If you start with
a completely different
approach to building
medicine from top to bottom by
establishing high-standard facili­
ties, there is a possibility you can
start training qualified personnel
and helping other centers not at the
same level.
The Salam Center treats patients
whose hearts have been damaged
by rheumatic fever. Can you talk
about the epidemiology of that
illness in Africa?
Rheumatic fever is becoming the
leading cause of death in Africa.
The link to poverty is quite clear.
The World Health Organization esti­
mates that around 20 million people
have rheumatic fever in Africa. They
re­­quire two million hospitalizations
every year. One million need heart
surgery because of that. Two thirds
of those affected are children, and
there are 300,000 deaths every year.
Would there be more of a public
health benefit if you spent this money
on vaccines and antibiotics instead
of on more sophisticated care?
If you’re comparing the cost of
treatment of patients with heart dis­
ease with treatment of patients with
malaria, tuberculosis or hepatitis, the
cost of cardiac treatment is much
higher for sure. But this way of think­
ing makes sense if we’ve estab­
lished that the main fac­
tor determining what
we do for health is
money. The prob­
lem is not to put
one against the
other: malaria
versus rheumatic
fever. The prob­
lem is to under­
stand we have to
solve both problems.
How will you get
started with the
10 centers of
excellence you
are building?
We’re hoping to con­
struct a center of excel­
lence in pediatric sur­
gery in Uganda. In most
cases, it will correct
con­­genital de­­fects. Care will be free
of charge, and it won’t matter where
the patients come from. Uganda will
pay 20 percent of the overall cost of
the program. If we get the resources,
we will start in a very few months.
The hospital has already been de­­
signed by one of the greatest archi­
tects in the world, Renzo Piano, who
is a friend of Emergency. —Gary Stix
name
Gino Strada
age
65
title
Surgeon; Founder
of Emergency
(an Italian NGO)
location
Khartoum,Sudan
P R O F I L E
PAT E N T WAT C H
Using a
Smartphone to
Detect Cancer
Oral cancer is straightforward for dentists
to detect early on.They can easily identify
lesions in the mouth that are precancerous.
But for people living in parts of the world
with few dentists,these lesions can go undi-
agnosed until it is too late for effective treat-
ment.Now a patent application has been
filed for a device that aims to tackle that
problem,designed by Manu Prakash of
Stanford University and his colleagues.
Called OScan,the device has bite guides
to hold open a patient’s mouth and a mount
thatallowsasmartphoneordigitalcamerato
attachtothefront.Inthisway,healthworkers
in the field can easily photograph the inside
of a person’s mouth and send those images
wirelessly to an off-site dentist or medical
expert who can evaluate them for signs of
malignancy.IncountriessuchasIndia,where
therecanbeasfewasonedentistperquarter
of a million residents in rural areas and where
oralcanceraccountsformorethan40percent
of all cancer-related deaths,OScan has the
potential to save many lives.—Geoffrey Giller
© 2014 Scientific American

31. May 2014, ScientificAmerican.com 29
ADVANCES
PHARMACOLOGY
Pot Ingredient
for Epilepsy
A new marijuana-derived drug may treat
epileptic children, without the high
A rising number of epileptic
patients are using an alterna­
tive medicine to reduce their
seizures. The herb in question
is Cannabis sativa. Among the
users are some of the almost
100,000 American children
who have “intractable epilep­
sy,” which does not respond to
standard antiseizure medica­
tions. Some parents report
that marijuana helps to con­
trol their child’s seizures when
other standard drugs do not.
There is no pharmaceuti­
cal preparation of cannabis as
a drug. Instead parents must
personally buy pot at a medi­
cal marijuana dispensary—or
perhaps illegally—to help
their child.
The isolation of a chemical
in marijuana that may be in­­
volved with tamping down sei­
zures could soon change all
that. Cannabidiol is a purified
compound derived from can­
nabis that shows promise in
treating epilepsy in both adults
and children. The chemical,
which also is responsible for
some of the other health bene­
fits associated with medical
marijuana, is the main active
ingredient in a new drug
under investigation, called
Epidiolex, manufactured by
GW Pharmaceuticals. Epidio­
lex contains several other can­
nabinoid compounds but is
formulated without tetrahy­
drocannabinol, the compound
that makes people feel high.
As with some approved
seizure medications, research­
ers do not understand exactly
how cannabidiol functions as
an anticonvulsant. Whatever
its physiological underpin­
nings, cannabidiol seems to
work. Animal studies and pre­
liminary investigations with
human adults suggest it sig­
nificantly reduces seizures
and is well tolerated and safe.
Now researchers are mak­
ing formal efforts to test can­
nabidiol in children with in­­
tractable epilepsy. A year-long
clinical trial will test whether
it diminishes epileptic activity
in 150 children who have not
been helped by standard sei­
zure medications. If Epidiolex
proves itself, it will supply ad­­
ditional evidence that mari­
juana may serve as a potential
cornucopia of medical leads
to be used for future drug
development.—Annie Sneed
© 2014 Scientific American

33. May 2014, ScientificAmerican.com 31
The Science of Health by Dina Fine Maron
Television advertisements for cigarettes have been banned in
the U.S. since 1971, but in the past few years supposedly healthi-
er, battery-powered alternatives have landed numerous prime-
time appearances. Electronic cigarettes, or e-cigs, as they are
known, soaked up the spotlight in recent Super Bowl commer-
cials, on late-night talk shows and in a comedy sketch during the
2014 Golden Globe Awards. Indeed, a recent survey shows that
nearly 60 percent of Americans are now familiar with the sleek,
smokeless devices.
The concept behind e-cigs is clever: they allegedly offer all
the fun of typical cigarettes without any of the dangers. E-cigs
use a small, heated coil to vaporize a nicotine-laced solution
into an aerosol mist. By inhaling the mist, users enjoy the same
satisfaction they would get from an ordinary cigarette but do
not expose themselves to tobacco, which turns into cancer-caus-
ing tar when it is burned. Such products free smokers from hud-
dling in the cold or rain and, in many places, from ordinances
that forbid smoking in public places.
But are e-cigs truly safe? No one knows for sure. Yet there is no
question that the nicotine they contain is addictive—which is one
reason many public health experts have grown alarmed by their
rapidly increasing popularity. Among their concerns: e-cigs might
lure former smokers back to conventional
cigarettes, expose users and bystanders alike
to unidentified dangers, or become a gateway
for teens who might subsequently experi-
ment with tobacco products and other drugs.
The U.S. Food and Drug Administration
and the European Union are grappling with
these issues as they decide how to regulate
the products. Unfortunately, they must act
before all the facts are available. Unfettered
access could leave people vulnerable to un­­
known health hazards, but there is also the
chance that greater restrictions might hurt
folks who are trying to forgo conventional—
and more dangerous—tobacco products.
FIRST PUFFS
The current iteration of e-cigarettes was
invented and popularized by Chinese phar-
macist Hon Lik in 2003 and entered the U.S.
market some seven years ago. (Earlier at­­
tempts at a “smokeless, non-tobacco ciga-
rette,” patented in 1965, never caught on.)
Initially the fda tried to regulate them as
drug-delivery devices, defined under federal
law as items “intended to affect the structure
or any function of the body.” E-cigarette
company NJOY sued the agency, however,
arguing that nicotine-containing devices were
similar to tobacco products—which the fda had also previously
tried and failed to have declared drug-delivery systems. A federal
appeals court ruled in December 2010 that the agency lacked
authority over e-cigs because they offer only the recreational
benefits of a regular cigarette. That legal decision allowed sales
of e-cigarettes to proceed but left many questions about their
safety unaddressed.
In lieu of carcinogenic tobacco, e-cigarettes typically contain
three main ingredients: nicotine, a flavoring of some kind and
propylene glycol—a syrupy synthetic liquid added to food, cos-
metics, and certain medicines to absorb water and help them
stay moist. The primary established danger of nicotine is that the
stimulant is highly addictive, although emerging science also
links it to an impaired immune system. Propylene glycol has
been “generally recognized as safe,” or GRAS (an official fda des-
ignation), since 1997. Yet more needs to be understood before
e-cigarettes can be a given a clean bill of health.
Propylene glycol, for example, is usually eaten (in cupcakes,
soft drinks and salad dressings) or slathered onto the body (in
soaps, shampoos and antiperspirants)—not breathed into the
lungs. Many things that can be safely eaten—such as flour—can
damage the lungs when inhaled. No one knows whether propyl-
Are E-Cigarettes Safe?
Even without tobacco, the poorly regulated
devices may pose unique dangers
Illustration by Tom Whalen
© 2014 Scientific American

34. 32 Scientific American, May 2014
The Science of Health
ene glycol falls into that category. “We have little information
about what happens to propylene glycol in the air,” the federal
Agency for Toxic Substances and Disease Registry says on its
Web site. An assessment from the agency, issued in 2008, refer-
ences only a couple of studies that cover inhalation exposures—
all with laboratory animals rather than people.
Beyond the three main ingredients, some researchers worry
about by-products from heating electronic cigarettes and the
solution inside them. Various studies suggest the vapors from
e-cigarettes contain several cancer-causing substances, as well as
in­­credibly tiny particles of tin, chromium,
nickel and other heavy metals, which, in
large enough concentrations, can damage
the lungs. These particles likely fleck off the
solder joints or metal coil in the devices
when heated. Because they are so small,
the tiniest bits of metal, known as nanopar-
ticles, can travel deep into the lungs. There
they could exacerbate asthma, bronchitis—
an inflammation of the tubes that carry air
to and from the lungs—and em­­physema—a
disease in which the lungs’ many air sacs
are de­­stroyed, leaving pa­­tients short of
breath. So far there are not enough data to
say with certainty whether e-cigs worsen
these disorders.
Craig Weiss, president and CEO of
NJOY, went on NPR during the summer
and espoused the safety of e-cigarettes,
pointing to “clinical trial” data he said would soon be published
in peer-reviewed literature. When Scientific American requested
that study, it received a draft of a small study looking at the use of
e-cigs for short-term smoking reduction, not the kind of large,
long-term, rigorously conducted trial that has become the gold
standard in medicine. “It is not a study that would lead to drug
approval,” admits Joshua Rabinowitz, NJOY’s chief scientist, but
a clinical trial “is defined as a test of biological response in a
human in a clinical setting, and that is exactly what was done.”
The few scientists actively trying to fill the gap in the research
literature are running into obstacles. When studying tobacco cig-
arettes, researchers rely on smoking machines that simulate how
frequently a typical smoker takes a puff and how much smoke is
inhaled with each breath. No one has yet determined how much
e-cig vapor the typical user breathes in, so different studies
assume different amounts of vapor as their standard, making it
difficult to compare their results. Tracing what happens to that
vapor once it is inhaled is equally problematic. When the human
body breaks down a foreign substance, one can typically find
chemical by-products in hair or urine that provide clues about
how it has interacted with cells. This is true for nicotine, but in
the case of propylene glycol, no one has established what the rel-
evant by-product is or how to best detect it.
WILD WEST
As scientists struggle to test the safety of e-cigarettes, the devic-
es are becoming more and more popular among teens and pre-
teens. E-cigarette use among U.S. high school students more
than doubled from 4.7 percent in 2011 to 10 percent in 2012,
according to recent data from the Centers for Disease Control
and Prevention’s National Youth Tobacco Survey. At least 160,000
students who had never tried conventional cigarettes puffed on
e-cigs. Yet another analysis linked e-cig use with greater odds of
trying tobacco. They come in kid-friendly flavors, including choc-
olate, bubble gum and gummy bear. Sold online and in the mall,
e-cigarettes are also easy for minors to acquire.
Federal legislative milestones that protect youngsters from
conventional cigarettes—such as blocking sales to minors and
preventing commercials targeted at ado-
lescents—do not exist for e-cigarettes. In
an attempt to remedy the situation, 40
state attorneys general signed a letter last
September urging the fda to assume “im­­
mediate regulatory oversight of e-ciga-
rettes, an increasingly widespread, ad­­dic­
tive product.”
Yet there has been hardly any definitive
legislation regarding the sale and con-
sumption of e-cigs in the U.S. Meanwhile
Canada has made it illegal to sell e-ciga-
rettes preloaded with nicotine in stores,
but the regulation is not well enforced,
and customers can buy vials of nicotine
online. Things are slightly better across
the pond. At press time, the European Par-
liament had approved a ban on e-cigarette
advertising starting in mid-2016, and the
ban seemed likely to get approval from the E.U.’s member states.
Without regulations, it is the “Wild West” for e-cigarette
companies, says Stanton Glantz, director of the Center for To­­
bacco Control Research and Education at the University of Cali-
fornia, San Francisco, and a self-described e-cigarette pessimist.
He argues that given the paucity of health data, current indoor
smoking bans should apply to e-cigs as well. “One of the real
problems [with] these things is that because of the low quality
control, you never quite know what you are getting,” he says.
Those who support minimal regulation contend that limiting
the use of e-cigarettes would encourage more people to smoke
conventional cigarettes.
As the debate blazes, deep-pocketed big tobacco investors
are buying up e-cig companies, injecting millions of dollars into
the market and banking on a bright future for the devices. More
than 100 e-cigarette companies are now jockeying for the busi-
ness of smokers and nonsmokers alike. The success of all these
enterprises hinges on the claim that e-cigarettes are healthier
than traditional cigarettes. Companies like to paint a black-and-
white picture of a new era of safe smoking. “Cigarettes, you’ve
met your match,” NJOY proudly proclaims in its Super Bowl
ads. Whether e-cigs are genuinely safe is far hazier.
Dina Fine Maron is an associate editor at Scientific American.
SCIENTIFIC AMERICAN ONLINE
Comment on this article at ScientificAmerican.com/may2014
Vapors from
electronic
cigarettes
contain several
cancer-causing
substances,
as well as tiny
particles of
tin, chromium
and nickel.
© 2014 Scientific American

35. TechnoFiles by David Pogue
May 2014, ScientificAmerican.com 33
David Pogue is the anchor columnist forYahooTech
and host of several NOVA miniseries on PBS.
Illustration by Jeffrey Alan Love
Fear
the Worst
A little outrage over
new technology can be
a good thing
It’s human to fear new technology.
We instinctively worry about almost
anything that is unknown, probably
for sound evolutionary reasons. And in
the Fear of the Un­known Department,
technologies probably top the list.
It’s nothing new. In the 1970s micro-
wave ovens were said to leak radiation
and cause birth defects. In the 1950s TV
was supposed to rot our brains. In the
1930s people worried that radio would
be too stimulating for children’s excit-
able minds, harming their school per-
formance. In the 1800s the tractor, on
its first appearance in farmers’ fields,
was thought to be the devil’s work.
New technologies now arrive (and
de­­­­­part) faster than ever. We scarcely
have the time to adjust to one status
quo before it changes again.
No wonder, then, that our fears for
the future are also blooming like crazy.
Today we fear the effect of electron-
ics on our children, their brains and their ability to socialize. We
know that big companies and the government are collecting our
data, and we are afraid for our privacy. We fret that cell phones
give us brain cancer. We worry that the country’s 82,000 fracking
wells, which push natural gas out of underground shale, may
create environmental catastrophe.
It’s true that our fears often turn out to be needless (tractors
were fairly benign instruments of agriculture). Some modern
fears may be misplaced, and some may be genuine causes for
alarm; we just don’t know yet. These topics are controversial pre-
cisely because all the research isn’t in. Besides, every now and
then, the public’s fear of an unfamiliar technology is well found-
ed. Thalidomide, a treatment for morning sickness, really did
cause birth defects. Cell phone–addled drivers really do kill thou-
sands of people a year. The National Security Agency really was
snooping on Americans.
Should we think about giving up, then? Should we call a five-
year moratorium on progress while we
assess what we’re doing? Should we
abandon technology for a simpler life?
Well, that’s one option. But the sur-
prising thing about reasonable fear is
that it can be healthy—when it’s chan-
neled into outrage. And just as we have
a long tradition of fearing new technol-
ogies, we have another long, proud tra-
dition: course correction.
Give us enough time, and we guide
ourselves back onto the tracks almost
every time.
Sometimes the transgressions are
mi­­nor: Face­book overreached in a new
privacy statement, Verizon be­­gan charg-
ing customers $2 a month for making
online payments, Net­flix announced it
would spin off its DVD company, the
Federal Aviation Ad­­min­­istration banned
perfectly harmless gadgets like e-book
readers. In each case, public outrage
forced the transgressors to retreat.
Sometimes the issues that come up
are more serious. Once the science is
in, we usually manage to phase out
what’s killing us (thalidomide, trans
fats). Eventually we also get around to
phasing out what’s killing our planet
(sulfur emissions, chlorofluorocarbons).
Many people believe that the nsa
scandal was a blight on our govern-
ment’s reputation. I agree. But the re­­
sulting outrage has been fantastic. We
don’t know yet what kind of limits will be put on the nsa’s ac­­
tions, although you can bet that its days of entirely unsuper-
vised freedom are over.
Meanwhile the national conversation about privacy triggered
a ripple effect. As a result of the nsa revelations, the big tech com-
panies (Google, Yahoo, Facebook, and so on) now encrypt all their
data to and from your computer. The public is demanding to
know exactly what those companies do with our data—and now
know to keep a better eye on them to make sure they tell the truth.
Technology will always change us, and it will always frighten
us, but we will push back when necessary. Okay, not every time
and not always promptly. In general, though, we can count on
the beneficial results of outrage, course corrections—and fear.
SCIENTIFIC AMERICAN ONLINE
A brief history of outrage: ScientificAmerican.com/may2014/pogue
© 2014 Scientific American

36. Photograph by Tktk Tktk
Crısıs
Physıcs
ın
Supersymmetry
andthe
PARTICLE PHYSICS
For decades physicists have been working on
a beautiful theory that has promised to lead to
a deeper understanding of the quantum world.
Now they stand at a crossroads: prove it right in
the next year or confront an epochal paradigm shift
By Joseph Lykken and Maria Spiropulu
I N B R I E F
Supersymmetry postulates that every known parti­
cle has a hidden superpartner. Physicists love super­
symmetry because it solves a number of problems
that crop up when they try to extend our under­
standing of quantum mechanics.It would also poten­
tially solve the mystery of the universe’s missing
dark matter.
Physicists hoped to find evidence of supersymmetry
inexperimentsattheLargeHadronCollider(LHC).To
date, they have not. If no evidence arises in the next
run of the LHC,supersymmetry will be in trouble.
The failure to find superpartnersisbrewingacrisisin
physics,forcing researchers to question assumptions
from which they have been working for decades.
34 Scientific American, May 2014
© 2014 Scientific American

37. Illustration by Artist Name , ScientificAmerican.com 35
CMS DETECTOR at the Large Hadron Collider will start its final search
for evidence of supersymmetry when the LHC starts back up in early 2015.
© 2014 Scientific American

38. 36 Scientific American, May 2014
At CERN, Maurizio Pierini, the Razor team’s leader, flashed a
plot of new data, and from nine time zones away we could see
the raised eyebrows around the room: there was an anomaly.
“Somebody should look at this event,” Pierini said matter-of-
factly. By “event” he meant a particular proton-proton collision,
one of trillions produced at the LHC. Within minutes the two of
us had pulled up the full record for this collision on a laptop.
Supersymmetry is an amazingly beautiful solution to the deep
troubles that have been nagging at physicists for more than four
decades. It provides answers to a series of important “why” ques-
tions: Why do particles have the masses they do? Why do forces
have the strengths they do? In short: Why does the universe look
the way it does? In addition, supersymmetry predicts that the
universe is filled with heretofore hidden “superpartner” particles
that would solve the mystery of dark matter. It is not an exaggera-
tion to say that most of the world’s particle physicists believe that
supersymmetry must be true—the theory is that compelling.
These physicists’ long-term hope has been that the LHC would
finally discover these superpartners, providing hard evidence
that supersymmetry is a real description of the universe.
As we pulled up the interesting collision, we immediately saw
that it appeared to be a smoking-gun signal of supersymmetry.
Two clusters of very energetic particles were observed moving
one way, recoiling against something unseen—perhaps a super-
partner? Yet soon enough we noticed a big red spike on the read-
out. Could this be a fake signal from a detector malfunction?
And so it turned out—another disappointment in the seemingly
unending quest to find supersymmetry.
Indeed, results from the first run of the LHC have ruled out
almost all the best-studied versions of supersymmetry. The nega-
tive results are beginning to produce if not a full-blown crisis in
particle physics, then at least a widespread
panic. The LHC will be starting its next run
in early 2015, at the highest energies it was
designed for, allowing researchers at the
ATLAS and CMS experiments to uncover
(or rule out) even more massive superpart-
ners. If at the end of that run nothing new
shows up, fundamental physics will face a
crossroads: either abandon the work of a
generation for want of evidence that na­­
ture plays by our rules, or press on and
hope that an even larger collider will some-
day, somewhere, find evidence that we
were right all along.
Of course, the story of science has many examples of long
quests succeeding triumphantly—witness the discovery of the
long-sought Higgs boson at the LHC. But for now most particle
theorists are biting their nails, as LHC data are about to test the
foundations of the mighty cathedral of theoretical physics that
they have built up over the past half-century.
THE NEED FOR SUPERSYMMETRY
Supersymmetry is part of a broader attempt to understand the big
mysteries of quantum weirdness. We have a fantastically success-
ful and predictive theory of subatomic physics, prosaically known
as the Standard Model, which combines quantum mechanics
with Einstein’s special theory of relativity to describe particles
and forces. Matter is made of one variety of particles called fermi-
ons (after Enrico Fermi) and held together by forces related to
another type of particle called bosons (after Satyendra Bose).
The Standard Model provides an excellent description of
what goes on in the subatomic world. But we begin to get into
trouble when we ask the questions of why the Standard Model
has the features that it does. For example, it holds that there are
three different types of leptons (a type of fermion): the electron,
muon and tau. Why three? Why not two, or four, or 15? The Stan-
dard Model does not say; we need to explore a deeper level of
nature to discover the answer. Similarly, we might ask, Why does
the electron have the mass that it does? Why is it lighter than,
say, the Higgs boson? Again: on this, the Standard Model is silent.
Theoretical particle physicists spend a lot of time thinking
about such questions. They build models that explain why the
Standard Model looks the way it does. String theory, for exam-
ple, is one effort to get down to a deeper level of reality. Other
examples abound.
PRECEDINGPAGES:COURTESYOFCERN
on a summer morning in
2012, we were on our third round of espresso when the video
link connected our office at the California Institute of Technol-
ogy to the CERN laboratory near Geneva. On the monitor we
saw our colleagues on the Razor team, one of many groups of
physicists analyzing data from the CMS experiment at CERN’s
Large Hadron Collider (LHC). Razor was created to search for
exotic collisions that would provide the first evidence of super-
symmetry, a 45-year-old theory of matter that would supplant
the standard understanding of particle physics, solving deep
problems in physics and explaining the nature of the universe’s
mysterious dark matter. After decades of searching, no experi-
mental evidence for supersymmetry has been found.
dawn
At
Joseph Lykken is a theoretical physicist based at the
Fermi NationalAccelerator Laboratory in Batavia,Ill.
Maria Spiropulu is an experimental particle
physicist based at the California Institute ofTech­
nology.She searches for supersymmetry with the
CMS experiment at CERN’s Large Hadron Collider
after spending many years at Fermilab’sTevatron.
© 2014 Scientific American

39. May 2014, ScientificAmerican.com 37
COURTESYOFCERN(CMSconstruction);COURTESYOFCMSCOLLABORATION(CMSevent)
All these additional theories have a problem, however. Any
theory (like string theory) that involves new physics necessarily
implies the existence of new hypothetical particles. These par-
ticles might have an extremely high mass, which would explain
why we have not already spotted them in accelerators like the
LHC, as high-mass particles are difficult to create. But even
high-mass particles would still affect ordinary particles like the
Higgs boson. Why? The answer lies in quantum weirdness.
In quantum mechanics, particles interact with one another
via the exchange of so-called virtual particles that pop into and
out of existence. For example, the repulsive electric force between
two electrons is described, to first approximation, by the elec-
trons exchanging a virtual photon. Richard Feynman derived ele-
gant rules to describe quantum effects in terms of stable particles
interacting with additional virtual particles.
In quantum theory, however, anything that is not strictly for-
bidden will in fact happen, at least occasionally. Electrons will
not just interact with one another via the exchange of virtual
particles, they will also interact with all other particles—includ-
ing our new, hypothetical particles suggested by extensions of
the Standard Model. And these interactions would create prob-
lems—unless, that is, we have something like supersymmetry.
Consider the Higgs boson, which in the Standard Model
gives elementary particles mass. If you had a Higgs but also had
some superheavy particles, they would talk to one another via
virtual quantum interactions. The Higgs would itself become
superheavy. And the instant after that, everything in the uni-
verse would transform into superheavy particles. You and I
would collapse into black holes. The best explanation for why
we do not is supersymmetry.
THE PROMISE OF SUPERSYMMETRY
The basic idea of supersymmetry, generally known by the nick-
name “SUSY” (pronounced “Suzy”), was developed by physicists
in the 1970s who were interested in the relation between symme-
tries and particle physics. Supersymmetry is not one particular
theory but rather a framework for theories. Many individual
models of the universe can be “supersymmetric” if they share
certain properties.
Many ordinary symmetries are built into the physical laws for
particles and forces. These laws do not care about where you are,
when you do the measurement, what direction you are facing, or
whether you are moving or at rest with respect to the objects that
you are observing. These spacetime symmetries mathematically
imply conservation laws for energy, momentum and angular mo­­
mentum; from symmetries themselves, we can derive the relation
between energy, momentum and mass famously exemplified by
E = mc2. All of this has been pretty well understood since 1905,
when Albert Einstein developed special relativity.
Quantum physics seems to respect these symmetries. Scien-
tists have even used the symmetries to predict new phenomena.
For example, Paul Dirac showed in 1930 that when you combine
quantum mechanics with relativity, spacetime symmetries imply
that every particle has to have a related antiparticle—a particle
with opposite charge. This idea seemed crazy at the time because
no one had ever seen an antiparticle. But Dirac was proved right.
His theoretical symmetry arguments led to the bold but correct
prediction that there are about twice as many elementary parti-
cles as everyone expected.
Supersymmetry relies on an argument that is similar to
Di­rac’s. It postulates that there exists a quantum extension of
spacetime called superspace and that particles are symmetric in
this superspace.
Superspace does not have ordinary spatial dimensions like
left-right and up-down but rather extra fermionic dimensions.
Motion in a fermionic dimension is very limited. In an ordinary
spatial dimension, you can move as far as you want in any direc-
tion, with no restriction on the size or number of steps that you
take. In contrast, in a fermionic dimension your steps are quan-
tized, and once you take one step that fermionic dimension is
“full.” If you want to take any more steps, you must either switch
to a different fermionic dimension, or you must go back one step.
If you are a boson, taking one step in a fermionic dimension
turns you into a fermion; if you are a fermion, one step in a fermi-
onic dimension turns you into a boson. Furthermore, if you take
one step in a fermionic dimension and then step back again, you
will find that you have also moved in ordinary space or time by
some minimum amount. Thus, motion in the fermionic dimen-
sions is tied up, in a complicated way, with ordinary motion.
Why does all of this matter? Because in a supersymmetric
UPGRADES to the CMS experiment (left) will aid
in the search for supersymmetry. A positive signal of
supersymmetry would look much like this 2012 event
(above): two high-energy jets of particles on the low-
er half of the detector imply that missing matter—
perhaps a “dark” superpartner—is escaping above.
© 2014 Scientific American

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world, the symmetries across fermionic dimensions restrict how
particles can interact. In particular, so-called natural supersym-
metries greatly suppress the effects of virtual particles. Natural
supersymmetries prevent Higgs bosons from interacting with
high-energy particles in such a way that we all turn into black
holes. (Theories that are supersymmetric but not natural re­­quire
us to come up with additional mechanisms to suppress virtual
particles.) Natural supersymmetry clears the way for physicists to
develop new ideas to make sense of the Standard Model.
THE SEARCH FOR SUPERSYMMETRY
All supersymmetric theories imply that every boson particle
has a fermion partner particle, a superpartner, and vice versa.
Because none of the known boson and fermion particles seem
to be superpartners of one another, supersymmetry can be cor-
rect only if the universe contains a large number of superpart-
ner particles that have eluded detection.
Therein lies the rub. In the simplest, most powerful versions
of supersymmetry—natural supersymmetry—the superpart-
ners should not be that much heavier than the Higgs boson.
That means that we should be able to find them at the LHC.
Indeed, if you would have asked physicists 10 years ago, most
would have guessed that by now we should have already found
evidence of superpartners.
And yet we have not. One of us (Spiropulu) remembers the
night in 2009 that I went to work as a shift leader at the CMS
detector just before midnight. The control room was crowded
with physicists, each monitoring a different subsystem of the
massively complex, 14,000-metric-ton detector. At 2 a.m., I got a
call from the CERN Control Center on the opposite side of the
27-kilometer-long LHC ring: tonight was the night; they were
going for the highest-energy proton collisions ever attempted.
I gave the signals to carefully bring up each portion of the
CMS, keeping the more fragile parts of the detector for last. At
4:11 a.m., the full detector went live. A wall of monitors went
wild, with ultrafast electronics flashing displays of the collisions
happening 20 million times a second 100 meters below. After
chasing supersymmetry for a decade at Fermilab’s Tevatron col-
lider in Batavia, Ill., my heart leapt in anticipation of recognizing
certain patterns. Calm, I told myself, this is only the beginning—
it is seductive to analyze collisions by visual inspection, but it is
impossible to make a discovery like that.
Indeed, you don’t build a $10-billion collider with its giant de­­
tectors, turn it on and expect discoveries on the first night—or
even during the first year. Yet our expectations were high from the
very start. At CMS (and at ATLAS), we had laid out an elaborate
plan to discover supersymmetry with the first LHC data. We had
geared up to find dark matter particles in supersymmetry signals,
not directly but as “missing energy”: a telltale imbalance of vi­­sible
particles recoiling from something unseen. We even went so far as
to write a template for the discovery paper with a title and a date.
That paper remains unwritten. The experiments have left
only a few unexplored windows in which superpartners might
be hiding. They can’t be too light, or we would have found them
already, and they can’t be too heavy, because then they wouldn’t
satisfy the needs of natural supersymmetry, which is the type of
supersymmetry that is effective at suppressing virtual particles.
If the LHC does not find them during its next run—and does
not do so quickly—the crisis in physics will mount.
LIFE AFTER SUPERSYMMETRY
Theorists are not ready to give up on a more general idea of
supersymmetry, though—even if it cannot do all the work that
we were hoping natural supersymmetry would do. Recall that
supersymmetry is a framework for making models of the world,
not a model itself, so future data may vindicate the idea of super-
symmetry even if all current models are excluded.
During a talk at the Kavli Institute for Theoretical Physics at
the University of California, Santa Barbara, Nima Arkani-Hamed,
a physicist at the Institute for Advanced Study in Princeton, N.J.,
paced to and fro in front of the blackboard, addressing a packed
room about the future of supersymmetry. What if supersymme-
try is not found at the LHC, he asked, before answering his own
question: then we will make new supersymmetry models that put
the superpartners just beyond the reach of the experiments. But
wouldn’t that mean that we would be changing our story? That’s
okay; theorists don’t need to be consistent—only their theories do.
This unshakable fidelity to supersymmetry is widely shared.
Particle theorists do admit, however, that the idea of natural
supersymmetry is already in trouble and is headed for the dust-
bin of history unless superpartners are discovered soon. This is
the kind of conundrum that has in the past led to paradigm shifts
in science. For example, more than a century ago the failure to find
the “luminiferous ether” led to the invention of special relativity.
C O S M I C C O N S E Q U E N C E S
The Edge of Doom
The Higgs boson reveals a lot about the Higgs field, an energy
field that gives elementary particles mass. So far as we know,
this field is constant because any sudden change would de­­
stroy the universe. Yet the recently measured mass of the
Higgs boson, when combined with the top quark’s mass, indi­
cates that the Higgs field is not completely stable. Instead it is
in a so-called metastable state. Quantum effects could bounce
it into a lower energy state, annihilating the universe in the
process. (Don’t worry: it shouldn’t happen for many billions of
years.) Supersymmetry would help stabilize the Higgs field.
Higgs Mass (gigaelectron volts)
TopQuarkMass(gigaelectronvolts)
0 50 100 150 200
200
150
100
50
0
Unstable (black)
Stable (green)
Measured values
Metastable (blue)
How the LHC is being rebuilt in an effort to find supersymmetry (and more)—watch a video at ScientificAmerican.com/may2014/lhcSCIENTIFIC AMERICAN ONLINE
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